2. Radiation: Patients must not have received radiation for a minimum of two weeks prior to study entry. Patients who received radiation to the only site of MIBG-avid disease within two months of study entry require biopsy confirmation of residual active disease, with positive bone marrow biopsy being adequate confirmation of residual active disease. A minimum of 3 months is required following prior large field radiation therapy (i.e. craniospinal therapy, total lung, > 50% marrow space). Patients are excluded if they have received whole abdominal radiation or TBI (total body irradiation).